Method and apparatus for TTI bundling transmission in a wireless communications system

ABSTRACT

A method for handling a transmission time interval, hereinafter called TTI, bundling operation for a mobile device of a wireless communication system is disclosed. The method includes performing transmission of a TTI bundle, and ignoring all feedbacks and uplink grants for retransmission when the feedbacks and uplink grants for retransmission are received after the transmission of the TTI bundle and before the TTI where a feedback of the TTI bundle is expected.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/111,734, filed on Nov. 6, 2008 and entitled “METHOD AND APPARATUS FORTTI BUNDLING TRANSMISSION IN A WIRELESS COMMUNICATIONS SYSTEM” thecontents of which are incorporated herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method utilized in a wirelesscommunication and communication device thereof, and more particularly,to a method of handling TTI bundling operation improving transmission ina wireless communication system and communication device thereof.

2. Description of the Prior Art

A long-term evolution (LTE) system, initiated by the third generationpartnership project (3GPP), is now being regarded as a new radiointerface and radio network architecture that provides a high data rate,low latency, packet optimization, and improved system capacity andcoverage. In the LTE system, an evolved universal terrestrial radioaccess network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs)and communicates with a plurality of mobile stations, also referred asuser equipments (UEs).

A radio interface protocol of the LTE system includes three layers: thePhysical Layer (L1), the Data Link Layer (L2), and the Network Layer(L3), wherein a control plane of L3 is a Radio Resource Control (RRC)layer, and L2 is further divided into a Packet Data Convergence Protocol(PDCP) layer, a Radio Link Control (RLC) layer and a Medium AccessControl (MAC) layer.

The main services and functions of the MAC layer include mapping betweenlogical channels and transport channels; multiplexing/demultiplexing ofRLC PDUs belonging to one or different radio bearers into/from transportblocks (TB) delivered to/from the physical layer on transport channels;buffer status reporting; power headroom reporting; error correctionthrough HARQ (Hybrid Automatic Repeat Request); priority handlingbetween logical channels of one UE; priority handling between UEs bymeans of dynamic scheduling; TTI (Transmission Time Interval) bundlingtransmission and padding.

TTI bundling transmission is introduced to improve LTE uplink coveragewithout the issues of overhead associated with L2 segmentation and ACK(Acknowledgement)/NACK (Negative Acknowledgement) errors. The UEs incell boundary can reduce transmission delay by means of TTI bundlingtransmission. The activation and deactivation of TTI bundlingtransmission is controlled by RRC signaling message, e.g. RRC ConnectionReconfiguration message.

In the MAC layer, adaptive and non-adaptive retransmissions are used.The adaptive retransmissions is performed on resources with a MCS(Modulation and Coding Scheme) indicated on a PDCCH (Physical DownlinkControl Channel). The non-adaptive retransmission is performed on thesame resource and with the same MCS as was used for the last madetransmission attempt.

If TTI bundling is configured by the RRC layer, a parameterTTI_BUNDLE_SIZE provides the number of TTIs of a TTI bundle. Within aTTI bundle, HARQ retransmissions are non-adaptive and shall be performedwithout waiting for feedbacks (e.g. NACK or ACK) related to previoustransmissions according to the parameter TTI_BUNDLE_SIZE. A feedback fora TTI bundle is only received for a specific TTI corresponding toTTI_BUNDLE_SIZE. A retransmission of a TTI bundle is also a TTI bundle.For transmission of an uplink message containing a C-RNTI (Cell RadioNetwork Temporary Identifier) MAC control element or an uplink messageincluding a CCCH (Common Control Channel) SDU (Service Data Unit) duringa random access procedure, the TTI bundling does not apply.

Activation and deactivation of TTI bundling transmission are configuredby RRC signaling message. However, TTI bundling transmission is done inMAC/PHY layers. Therefore, the activation or deactivation of the TTIbundle may not be synchronized between the UE and the eNB. When the UEand the eNB activate or deactivate the TTI bundling operation in thedifferent time, transmission interference or degradation of the systemperformance can occur.

Take an issue 1 for example. Please refer to FIG. 1, which is aschematic diagram of a TTI bundling operation according to the priorart. The UE activates the TTI bundling operation with a HARQ process id(identity) 0 at TTI 1. The TTI_BUNDLE_SIZE is set to 4. In thissituation, transport blacks of the TTI bundle are transmitted from TTI 1to TTI 4. When activation or deactivation of the TTI bundling operationis not synchronized between the UE and the eNB, the UE receives thefeedback of the TTI bundle in the wrong TTI as being shown in FIG. 1where an HARQ NACK is received in TTI 5. On the standpoint of the UE,the UE does not know if the received feedback corresponds to the TTIbundle or not.

The prior art does not specify when the UE shall perform aretransmission for a TTI bundling transmission after the feedback of theTTI bundling transmission is received. According to the prior art, aretransmission of a non-TTI-bundling transmission is performed in aTTI(n+4) when a feedback of the non TTI bundling transmission isreceived in a TTI(n). If a non-adaptive retransmission of the TTI bundlein FIG. 2 is performed based on the foregoing specification clause andthereby performed in TTI 9, the system performance may be downgradedsince the non-adaptive retransmission is unnecessary (if the HARQ NACKdoes not correspond to the TTI bundle) or causes interference totransmissions of other UEs. For example, if a UE1 performs thenon-adaptive retransmission in TTI 9 that has been allocated to a UE2 bythe eNB due to the lack of synchronization of the TTI bundlingactivation, the transmission interference occurs.

Take an issue 2 for example. Please refer to FIG. 2, which is aschematic diagram of a TTI bundling operation according to the priorart. The TTI bundling operation is activated at the UE with a HARQprocess id 0, and corresponding transport blocks are transmitted in aTTI bundle of TTIs 1-4. Due to the lack of synchronization of the TTIbundling activation, a HARQ ACK for the TTI bundle is received in TTI 5.No HARQ ACK is received in TTI 8 where the UE shall receive a feedbackof the TTI bundle. As a result, a retransmission of the TTI bundleoccurs in TTIs 17, 18, 19, and 20, configured by RRC signaling accordingto the prior art. This retransmission is unnecessary and wastes UE powersince the eNB has feedback with the HARQ ACK for the TTI bundle. Inaddition, the retransmission may make interference to other UEs if anyof the TTIs 17-20 has been allocated to other UEs.

In addition to the feedback, PDCCH information may be received duringthe period of waiting the feedback of a TTI bundle. The prior art doesnot specify how the UE shall deal with this situation, and thereby cancause an unnecessary retransmission or transmission interference.

Take an issue 3 for example. Please refer to FIG. 3, which is aschematic diagram of a TTI bundling operation according to the priorart. The TTI bundling operation is activated at the UE with a HARQprocess id 0, and corresponding transport blocks are transmitted in aTTI bundle of TTIs 1-4. PDCCH information carrying an uplink (UL) grantincluding a MCS for an adaptive retransmission is received in TTI 5.This means that the eNB indicates the UE to perform an uplinktransmission with the MCS in the adaptive way. If the adaptiveretransmission in TTI 9 (5+4) occurs, the system performance isdowngraded due to the unnecessary retransmission or transmissioninterference to other UEs.

During TTI bundling transmission, the UE possibly receives a request fordeactivating the TTI bundling operation, also causing an unnecessaryretransmission or transmission interference.

Take an issue 4 for example. Please refer to FIG. 4, which is aschematic diagram of a TTI bundling operation according to the priorart. The TTI bundling operation is activated at the UE with a HARQprocess id 0, and corresponding transport blocks are transmitted in aTTI bundle of TTIs 1-4. The UE does not receive a HARQ NACK in TTI 8,and thereby a retransmission is configured to be performed in a TTIbundle of TTIs 17-20. The TTI bundling is deactivated at the UE with aHARQ process id 0 in TTI 18. According to the prior art, retransmissionsin TTI 19 and 20 are cancelled. However, the prior art does not clearlyspecify when the UE receives a HARQ feedback of the retransmission. Ifthe HARQ feedback of the retransmission is a NACK, the 2ndretransmission shall be performed. Even according to the retransmissionclause for the non TTI bundling operation, the prior art does notspecify that the UE shall perform the retransmission in TTI 22 or TTI24. The 2nd retransmission is possibly performed at a TTI unexpected bythe eNB, and thus an unnecessary retransmission or transmissioninterference to other UEs occurs, thereby downgrading the systemperformance.

Take an issue 5 for example. In the prior art, the TTI bundlingoperation does not apply for transmission of the uplink messagecontaining the C-RNTI MAC control element or the uplink messageincluding the CCCH SDU during the random access procedure(contention-based random access). On the other hand, the TTI bundlingoperation is applied for an MAC PDU transmission granted by a randomaccess response which is triggered by a PDCCH order with a dedicatedpreamble (non-contention-based random access). Since the MAC PDU grantedby the random access response contains no uplink data, using the TTIbundle to transmit the MAC PDU makes unnecessary retransmissions andwastes UE power.

SUMMARY OF THE INVENTION

Therefore, the present invention provides a method of handling a TTIbundling operation in a wireless communication system and relatedcommunication device to avoid transmission interference, unnecessaryretransmissions, and a power waste.

According to an embodiment of the present invention, a method forhandling a TTI bundling operation for a mobile device of a wirelesscommunication system includes performing transmission of a TTI bundle,and ignoring all feedbacks and uplink grants for retransmission when thefeedbacks and the uplink grants for retransmission are received afterthe transmission of the TTI bundle and before the TTI where the feedbackof the TTI bundle is expected.

According to another embodiment of the present invention, a method forhandling a TTI bundling operation for a mobile device of a wirelesscommunication system includes transmitting a transport block in a firstTTI bundle, and retransmitting the transport block when anon-positively-acknowledged feedback or an uplink grant forretransmission is received after the transport block transmission of thefirst TTI bundle and before a TTI where a feedback of the first TTIbundle is expected.

According to another embodiment of the present invention, a method forhandling a TTI bundling operation for a mobile device of a wirelesscommunication system includes initiating transmission of a TTI bundle,continuing the transmission of the TTI bundle when a TTI bundlingdeactivation request is received during the transmission of the TTIbundle, and deactivating the TTI bundling operation according to the TTIbundling deactivation request when the transmission of the TTI bundle isfinished.

According to another embodiment of the present invention, a method forhandling a TTI bundling operation for a mobile device of a wirelesscommunication system includes initiating transmission of a TTI bundle,and when a TTI bundling deactivation request is received in a TTI of theTTI bundle, stopping the transmission of the TTI bundle in a TTIfollowing the TTI of the TTI bundle.

According to another embodiment of the present invention, a method forhandling a TTI bundling operation for a mobile device of a wirelesscommunication system includes configuring transmission of a packet thatcorresponds to random access and that includes no data to beinapplicable for the TTI bundling operation.

According to another embodiment of the present invention, acommunication device of a wireless communication system forappropriately handling a TTI bundling operation includes a computerreadable recording medium, a processor, a communication interfacingunit, and a control unit. The computer readable recording medium is usedfor storing program code corresponding to a process. The processor iscoupled to the computer readable recording medium and used forprocessing the program code to execute the process. The communicationinterfacing unit is used for exchanging signals with a peercommunication device of the wireless communication system. The controlunit is coupled to the processor and communication interfacing unit, andused for controlling the communication interfacing unit and thecommunication device according to processing results of the processor.The process includes performing transmission of a TTI bundle, andignoring all feedbacks and uplink grants for retransmission when thefeedbacks and the uplink grants for retransmission are received afterthe transmission of the TTI bundle and before the TTI where the feedbackof the TTI bundle is expected.

According to another embodiment of the present invention, acommunication device of a wireless communication system forappropriately handling a TTI bundling operation includes a computerreadable recording medium, a processor, a communication interfacingunit, and a control unit. The computer readable recording medium is usedfor storing program code corresponding to a process. The processor iscoupled to the computer readable recording medium and used forprocessing the program code to execute the process. The communicationinterfacing unit is used for exchanging signals with a peercommunication device of the wireless communication system. The controlunit is coupled to the processor and communication interfacing unit, andused for controlling the communication interfacing unit and thecommunication device according to processing results of the processor.The process includes transmitting a transport block in a first TTIbundle, and retransmitting the transport block when anon-positively-acknowledged feedback or an uplink grant forretransmission is received after the transport block transmission of thefirst TTI bundle and before a TTI where a feedback of the first TTIbundle is expected.

According to another embodiment of the present invention, acommunication device of a wireless communication system forappropriately handling a TTI bundling operation includes a computerreadable recording medium, a processor, a communication interfacingunit, and a control unit. The computer readable recording medium is usedfor storing program code corresponding to a process. The processor iscoupled to the computer readable recording medium and used forprocessing the program code to execute the process. The communicationinterfacing unit is used for exchanging signals with a peercommunication device of the wireless communication system. The controlunit is coupled to the processor and communication interfacing unit, andused for controlling the communication interfacing unit and thecommunication device according to processing results of the processor.The process includes initiating transmission of a TTI bundle, continuingthe transmission of the TTI bundle when a TTI bundling deactivationrequest is received during the transmission of the TTI bundle, anddeactivating the TTI bundling operation according to the TTI bundlingdeactivation request when the transmission of the TTI bundle isfinished.

According to another embodiment of the present invention, acommunication device of a wireless communication system forappropriately handling a TTI bundling operation includes a computerreadable recording medium, a processor, a communication interfacingunit, and a control unit. The computer readable recording medium is usedfor storing program code corresponding to a process. The processor iscoupled to the computer readable recording medium and used forprocessing the program code to execute the process. The communicationinterfacing unit is used for exchanging signals with a peercommunication device of the wireless communication system. The controlunit is coupled to the processor and communication interfacing unit, andused for controlling the communication interfacing unit and thecommunication device according to processing results of the processor.The process includes initiating transmission of a TTI bundle, and when aTTI bundling deactivation request is received in a TTI of the TTIbundle, stopping the transmission of the TTI bundle in a TTI followingthe TTI of the TTI bundle.

According to another embodiment of the present invention, acommunication device of a wireless communication system forappropriately handling a TTI bundling operation includes a computerreadable recording medium, a processor, a communication interfacingunit, and a control unit. The computer readable recording medium is usedfor storing program code corresponding to a process. The processor iscoupled to the computer readable recording medium and used forprocessing the program code to execute the process. The communicationinterfacing unit is used for exchanging signals with a peercommunication device of the wireless communication system. The controlunit is coupled to the processor and communication interfacing unit, andused for controlling the communication interfacing unit and thecommunication device according to processing results of the processor.The process includes configuring transmission of a packet thatcorresponds to random access and that includes no data to beinapplicable for the TTI bundling operation.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 are schematic diagrams of TTI bundling operations according tothe prior art.

FIG. 5 is a schematic diagram of a wireless communication system.

FIG. 6 is a schematic diagram of a communication device according to anembodiment of the present invention.

FIG. 7 is a schematic diagram of the program code for the LTE systemaccording to an embodiment of the present invention.

FIG. 8 is a flowchart of a process according to a first embodiment ofthe present invention.

FIG. 9 is a schematic diagram of a TTI bundling operation according toFIG. 8.

FIG. 10 is a flowchart of a process according to a second embodiment ofthe present invention.

FIG. 11 is a schematic diagram of a TTI bundling operation according toFIG. 10.

FIG. 12 is a schematic diagram of a TTI bundling operation according toFIG. 10.

FIG. 13 is a flowchart of a process according to a third embodiment ofthe present invention.

FIG. 14 is a schematic diagram of a TTI bundling operation according toFIG. 13.

FIG. 15 is a flowchart of a process according to a fourth embodiment ofthe present invention.

FIG. 16 is a schematic diagram of a TTI bundling operation according toFIG. 15.

FIG. 17 is a flowchart of a process according to a fifth embodiment ofthe present invention.

DETAILED DESCRIPTION

Please refer to FIG. 5, which illustrates a schematic diagram of awireless communication system 50 according to an embodiment of thepresent invention. Briefly, the wireless communication system 50 iscomposed of a network and a plurality of mobile devices. In FIG. 1, thenetwork and the mobile devices are simply utilized for illustrating thestructure of the wireless communication system 10. The wirelesscommunication system 50 can be a UMTS (Universal MobileTelecommunications System) or an LTE (long-term evolution) system. Inthe LTE system, the network is referred as a EUTRAN (evolved-UTRAN)comprising a plurality of eNBs, whereas the mobile devices are referredas user equipments (UEs). The UEs can be devices such as mobile phones,computer systems, etc. Besides, the network and the UE can be seen as atransmitter or receiver according to transmission direction, e.g., foruplink (UL), the UE is the transmitter and the network is the receiver,and for downlink (DL), the network is the transmitter and the UE is thereceiver.

Please refer to FIG. 6, which illustrates a schematic diagram of acommunication device 60 according to an embodiment of the presentinvention. The communication device 60 can be the mobile devices shownin FIG. 1 and includes a processor 600, a computer readable recordingmedium 610, a communication interfacing unit 620 and a control unit 630.The computer readable recording medium 610 is any data storage devicethat includes program code 614, thereafter read and processed by theprocessor 600. Examples of the computer readable recording medium 610include a subscriber identity module (SIM), read-only memory (ROM),random-access memory (RAM), CD-ROMs, magnetic tapes, hard disks, opticaldata storage devices, and carrier waves (such as data transmissionthrough the Internet). The control unit 630 controls the communicationinterfacing unit 620 and related operations and states of thecommunication device 60 according to processing results of the processor600. The communication interfacing unit 620 is preferably a radiotransceiver and accordingly exchanges wireless signals with the network.

Please refer to FIG. 7, which illustrates a schematic diagram of theprogram code 614 for the LTE system according to an embodiment of thepresent invention. The program code 614 includes program code ofmultiple communications protocol layers, which from top to bottom are aradio resource control (RRC) layer 700, a packet data convergenceprotocol (PDCP) layer 710, a radio link control (RLC) layer 720, amedium access control (MAC) layer 730 and a physical (PHY) layer 740.For packets of a layer, a service data unit (SDU) is a packet receivedfrom an upper layer, and a protocol data unit (PDU) is a packet thatincludes a header of the layer and zero or more SDUs and is transmittedto a lower layer.

The RRC layer 710 is used for configuring an activation state of a TTI(Transmission Time Interval) bundling operation and using aTTI_BUNDLE_SIZE parameter to set a size of a TTI bundle. The MAC layer730 is responsible for handling the TTI bundling operation, such ashandling activation and deactivation of the TTI bundling operation andhandling applicable targets, by itself or based on RRC configuration. Inaddition, the MAC layer 730 can perform HARQ (Hybrid Automatic RepeatRequest) processes for multiple transmissions of transport blocks and arandom access procedure including transmission of a random accesspreamble, reception of a random access response, and transmission of aMAC PDU including no uplink data. The PHY layer 740 is capable ofmonitoring a physical downlink control channel for receiving an uplinkgrant, HARQ information, etc.

Please refer to FIG. 8, which illustrates a flowchart of a process 80according to a first embodiment of the present invention. The process 80is utilized for handling a TTI bundling operation for a UE of a wirelesscommunication system. The process 80 can be compiled into the programcode 614 and includes the following steps:

Step 800: Start.

Step 810: Perform transmission of a TTI bundle.

Step 820: Ignore all feedbacks and uplink grants for retransmission whenthe feedbacks and the uplink grants for retransmission are receivedafter the transmission of the TTI bundle and before a TTI where afeedback of the TTI bundle is expected.

Step 830: End.

According to the process 80, the UE activates TTI bundling operation andperforms transmission of the TTI bundle by transmitting a plurality oftransport blocks in the TTI bundle. The UE ignores all the feedbacks(e.g. ACK or NACK) and the uplink grants for retransmission receivedafter the transmission of the TTI bundle and before the TTI where thefeedback of the TTI bundle is expected. Alternatively, after thetransmission of the TTI bundle and before the TTI where the feedback ofthe TTI bundle is expected, the UE stops reception of any feedbacks anduplink grants for retransmission. Preferably, the feedbacks are HARQfeedbacks.

When the activation or deactivation of the TTI bundling operation is notsynchronized between the UE and the eNB, the UE receives a feedback ofthe TTI bundle in a feedback-unexpected TTI. By ignoring or stoppingreceiving the feedbacks and the uplink grants, the UE eliminatespossibility of performing transmissions/retransmissions at the TTIsallocated to other UEs. Therefore, the transmission interference isavoided.

Take an example based on the concept of the process 80. Please refer toFIG. 9, which is a schematic diagram of a TTI bundling operationaccording to an embodiment of the present invention. In FIG. 9, the TTIbundling operation is activated at a UE with a HARQ process id 0, andcorresponding data is transmitted in a TTI bundle of TTIs 1-4 indicatingthat the TTI_BUNDLE_SIZE is set to 4. A TTI 8, derived from (a TTI4+four TTIs), is the TTI where a HARQ feedback of the TTI bundle isexpected (hereinafter also regarded as a TTI corresponding to theTTI_BUNDLE_SIZE). According to the process 80, the UE ignores HARQfeedbacks and uplink grants for retransmission during TTIs 5-7 andthereby ignores a HARQ NACK received in TTI 5. In other words, the UEonly considers an HARQ feedback or an uplink grant received in TTI 8. InFIG. 9, the UE receives no ACK in TTI 8, and a correspondingretransmission of the TTI bundle is configured in TTIs 17, 18, 19, and20. In this situation, a smart eNB is needed, capable of receiving andhandling retransmissions of the UE in a non synchronous HARQretransmission way in which the transmission and related retransmissiondo not have a fixed timing relationship.

Please refer to FIG. 10, which illustrates a flowchart of a process 1000according to a second embodiment of the present invention. The process1000 is utilized for handling a TTI bundling operation for a UE of awireless communication system. The process 1000 can be compiled into theprogram code 614 and includes the following steps:

Step 1010: Start.

Step 1015: Transmit a transport block in a TTI bundle.

Step 1020: Retransmit the transport block when anon-positively-acknowledged feedback or an uplink grant forretransmission is received after the transport block transmission of theTTI bundle and before a TTI where a feedback of the TTI bundle isexpected.

Step 1030: End.

According to the process 1000, the UE transmits the transport block inthe TTI bundle and retransmits the transport block when receiving thenon-positively-acknowledged feedback or the uplink grant forretransmission after the transport block transmission of the TTI bundleand before the TTI where the feedback of the TTI bundle is expected. TheUE can retransmit the transport block in another TTI bundle used forretransmission when the TTI bundling operation is still configured atTTI(s) of the TTI bundle used for retransmission. On the contrary, theUE can retransmit the transport block in a non-TTI-bundling way when theTTI bundling operation has been de-configured at the TTI(s) used forretransmission. The non-TTI-bundling way can be an adaptiveretransmission configured for only one TTI. Furthermore, the UE cancancel the retransmission of the transport block when the UE receives apositively-acknowledged feedback for any TTI of the TTI bundle orreceives an uplink grant for any TTI of the TTI bundle.

In the second embodiment, a smart eNB with a non synchronous HARQretransmission ability is needed.

Preferably, the non-positively-acknowledged feedback is a HARQ NACK orrepresents that neither HARQ ACK nor HARQ NACK is received; thepositively-acknowledged feedback is a HARQ ACK; the uplink grant forretransmission or for any TTI of the TTI bundle is received from aPDCCH.

Take an example based on the concept of the process 1000. Please referto FIG. 11, which is a schematic diagram of a TTI bundling operationaccording to an embodiment of the present invention. The UE performsactivation of the TTI bundling operation, transmission of a TTI bundle,and reception of a HARQ feedback in the same way as performed in FIG. 1.As can be seen from FIG. 11, a HARQ NACK is received in TTI 5 that is aTTI before the TTI corresponding to the TTI_BUNDLE_SIZE. The UEretransmits the transport block in TTI 9 in TTI bundling form(retransmits in TTIs 9-12) if the TTI bundling operation is stillconfigured in TTI 9 as shown in FIG. 11. The UE retransmits innon-TTI-bundling form (only retransmits in TTI 9) if the TTI bundlingoperation has been de-configured in TTI 9, not shown in FIG. 11.

Take another example based on the concept of the process 1000. Pleaserefer to FIG. 12, which is a schematic diagram of a TTI bundlingoperation according to an embodiment of the present invention. The UEperforms activation of the TTI bundling operation, transmission of a TTIbundle, and reception of a HARQ feedback in the same way as performed inFIG. 2. As can be seen from FIG. 12, a HARQ ACK is received in TTI 5that is considered a TTI corresponding to TTI 1 of the TTI bundle. Inthis situation, the UE cancels the retransmission of the transportblocks, which attempts to be transmitted in TTIs 17-20.

Please refer to FIG. 13, which illustrates a flowchart of a process 1300according to a third embodiment of the present invention. The process1300 is utilized for deactivating a TTI bundling operation for a UE of awireless communication system. The process 1300 can be compiled into theprogram code 614 and includes the following steps:

Step 1310: Start.

Step 1315: Initiate transmission of a TTI bundle.

Step 1320: Continue the transmission of the TTI bundle when a TTIbundling deactivation request is received during the transmission of theTTI bundle.

Step 1330: Deactivate the TTI bundling operation according to the TTIbundling deactivation request when the transmission of the TTI bundle isfinished.

Step 1340: End.

According to the process 1300, the UE initiates the transmission of theTTI bundle and then continues transmitting the TTI bundle when receivingthe TTI bundling deactivation request during the transmission of the TTIbundle. Furthermore, the UE deactivates the TTI bundling operationaccording to the TTI bundling deactivation request when the transmissionof the TTI bundle is finished. In other words, when the TTI bundlingdeactivation request during the transmission of the TTI bundle isreceived, the UE does not deactivate the TTI bundle operation untilfinishing the transmission of the TTI bundle.

Through the process 1300, the UE maintains a purpose of the TTI bundlingoperation, which aims to provide a high successful decoding rate of thetransmission data.

Take another example based on the concept of the process 1300. Pleaserefer to FIG. 14, which is a schematic diagram of a TTI bundlingoperation according to an embodiment of the present invention. The UEperforms activation of the TTI bundling operation, transmission of a TTIbundle, and reception of a HARQ feedback and a TTI bundling deactivationrequest in the same way as performed in FIG. 4. According to the conceptof the process 1300, the UE finishes retransmitting transport blocks ofTTIs 18-20 of the TTI bundle and then deactivates the TTI bundleoperation from TTI 21.

Please refer to FIG. 15, which illustrates a flowchart of a process 1500according to a fourth embodiment of the present invention. The process1500 is utilized for deactivating a TTI bundling operation for a UE of awireless communication system. The process 1500 can be compiled into theprogram code 614 and includes the following steps:

Step 1510: Start.

Step 1515: Initiate transmission of a TTI bundle.

Step 1520: When a TTI bundling deactivation request is received in a TTIof the TTI bundle, stop the transmission of the TTI bundle in a TTIfollowing the TTI of the TTI bundle.

Step 1530: Monitor a feedback of the TTI bundle in a feedback-expectedTTI corresponding to the TTI of a TTI bundle.

Step 1540: End.

According to the process 1500, the UE initiates the transmission of theTTI bundle. When receiving the TTI bundling deactivation request in aTTI of the TTI bundle (hereinafter denoted as TTI_1), the UE stopstransmission of the TTI bundle in next TTI. As a result, TTI_1 isconsidered the last TTI performing transmission in the TTI bundle. Afterthis, the UE monitors the feedback of the TTI bundle in afeedback-expected TTI corresponding to the TTI_1. In addition, if HARQtransmission is adopted, the UE can further monitor the feedback in afeedback-expected TTI corresponding to the last TTI of the TTI bundlewhen the UE does not transmit a transport block of a HARQ processdifferent from a HARQ process of the TTI bundle.

Alternatively, the UE can replace the action of Step 1530 withmonitoring the feedback of the TTI bundle in a feedback-expected TTIcorresponding to the last TTI of the TTI bundle.

In the fourth embodiment, the eNB is setup with retransmission clausebased on the process 1500, and thereby transmits the feedback in thefeedback-expected TTI corresponding to the TTI of the TTI bundle or tothe last TTI of the TTI bundle.

Take an example based on the concept of the process 1500. Please referto FIG. 16, which is a schematic diagram of a TTI bundling operationaccording to an embodiment of the present invention. The UE performsactivation of the TTI bundling operation, transmission of a TTI bundle,and reception of a HARQ feedback and a TTI bundling deactivation requestin the same way as performed in FIG. 4. According to the concept of theprocess 1500, the UE finishes transmitting a transport block of TTI 18of the TTI bundle and then stops TTI bundle operation from TTI 19. Afterthis, the UE monitors a feedback (the HARQ ACK or NACK) of the TTIbundle in TTI 22 (18+4) corresponding to TTI 18 that is the TTI for thelast transmission of the TTI bundle.

In the TTI bundling operation of FIG. 16, the UE can alternativelymonitor the feedback of the TTI bundle in TTI 24 (20+4) corresponding toTTI 20 that is the last TTI of the TTI bundle.

Please refer to FIG. 17, which illustrates a flowchart of a process 1700according to a fifth embodiment of the present invention. The process1700 is utilized for applying a TTI bundling operation for a UE of awireless communication system. The process 1700 can be compiled into theprogram code 614 and includes the following steps:

Step 1710: Start.

Step 1720: Only apply a non-TTI-bundling operation for transmission of apacket that corresponds to random access and includes no data.

Step 1730: End.

According to the process 1700, the UE only applies the non-TTI-bundlingoperation for the transmission of the packet that corresponds to randomaccess and includes no data. The packet includes no data herein can meanthat the packet only has header part. In other words, the transmissionof the packet is configured to be inapplicable for the TTI bundlingoperation. The process 1700 eliminates pure uplinksignaling/configuration TTI bundling transmission related tonon-contention-based random access since the signaling/configurationinformation is not used for soft combination, thereby saving UE power.

Preferably, the packet is a MAC PDU containing no uplink datacorresponding to an uplink grant received in a random access responsetriggered by a PDCCH order with a dedicated preamble. Or, the packet isa MAC PDU in a [Message3] buffer for a non-contension-based randomaccess procedure.

In conclusion, the embodiments of the present invention can prevent theUE from performing retransmissions in TTIs undesired by the network andeliminates TTI bundling transmission of pure random accesssignaling/configuration, so as to avoid transmission interference,unnecessary retransmissions, and a UE power waste.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A method for handling a transmission timeinterval, hereinafter called TTI, bundling operation for a mobile deviceof a wireless communication system, the method comprising: performingtransmission of a TTI bundle; and when at least one of a first feedbackand a first uplink grant for retransmission is received after thetransmission of the TTI bundle and before the TTI where a feedback ofthe TTI bundle is expected, ignoring all the first feedback and thefirst uplink grant for retransmission; wherein at least one of a secondfeedback and a second uplink grant for retransmission is not ignored ifat least one of the second feedback and the second uplink grant forretransmission is received during the TTI where the feedback of the TTIbundle is expected.
 2. The method of claim 1, wherein the TTI where thefeedback of the TTI bundle is expected is configured four TTIs laterafter the last TTI of the TTI bundle.
 3. The method of claim 1, whereinthe TTI where the feedback of the TTI bundle is expected is determinedaccording to a TTI bundle size.
 4. A communication device of a wirelesscommunication system for appropriately handling a transmission timeinterval, hereinafter called TTI, bundling operation, the communicationdevice comprising: a computer readable recording medium for storingprogram code corresponding to a process; and a processor coupled to thecomputer readable recording medium, for processing the program code toexecute the process; wherein the process comprises: performingtransmission of a TTI bundle; and when at least one of a first feedbackand a first uplink grant for retransmission is received after thetransmission of the TTI bundle and before the TTI where a feedback ofthe TTI bundle is expected, ignoring all first feedback and the firstuplink grant for retransmission; wherein at least one of a secondfeedback and a second uplink grant for retransmission is not ignored ifat least one of the second feedback and the second uplink grant forretransmission is received during the TTI where the feedback of the TTIbundle is expected.
 5. The communication device of claim 4, wherein theTTI where the feedback of the TTI bundle is expected is configured fourTTIs later after the last TTI of the TTI bundle.
 6. The method of claim4, wherein the TTI where the feedback of the TTI bundle is expected isdetermined according to a TTI bundle size.